DOOR LOCK SYSTEM

PROBLEM TO BE SOLVED: To perform door lock of all seats without fail by effecting key lock operation by a driver again when a passenger at a rear seat gets off a car and the door is brought into an unlocking state after a driver has got off with a door locked. SOLUTION: A door lock system is constituted such that when, in a state that all doors are locked through key lock operation of a driver's door, especially a rear seat door is unlocked and a passenger gets off from the interior of a car to the outside, a door opening/closing detecting signal outputted by a door opening closing detecting means 14 by opening and closing the rear seat door is received and an all seat unlock means 13 simultaneously unlocks all doors. Thus, in a situation that it is necessary to effect lock operation of a driver's seat door by a key, all doors are brought into an unlock state without fail, and such a state is prevented from occurring that one of rear seat doors is left unlocked as in a conventional type, even when lock operation is effected by a key.